The Final Experiment
by HipsterMaybe
Summary: So this is an AU version of last night's episode (4.06). I really changed a lot of stuff, so don't look for similarities, ok? I felt this needed a good dose of Danny whump/Steve angst, so I made it my own. Except... I don't own Hawaii Five-0 or any of that stuff. I don't wan t to give away too much, so just read and see!
1. Chapter 1

**I'm getting really busy with the fics here! Whew! I know I still need to finish Cat and Mouse and that I just started another multi chapter fic, but this one won't be too long. It popped into my head as kind of an AU version of last night's episode. Hope this comes out how I want. Basically, I changed the plot of the episode kind of a lot.**

As Steve chased the man from the complex tunnel system, he wondered how in the hell he was going to stop this guy. He was insanely fast and agile for such a scrawny man. As it turned out, _he_ didn't have to do anything. The man tripped on something moments after emerging into the forest. Steve quickly cuffed him to the door, but then felt his heart clench painfully in his chest as he saw what the man had tripped on. _Danny._ Steve ran over to his friend's side.

"Danny!" his eyes frantically scanned his partner for injuries. It wasn't until he noticed the blood beneath Danny's head that he realized where Danny was hurt. The wound wasn't deep, but it had bled a lot as head wounds do. "Danny, can you hear me? I need you wake up. That's it, Danno. Come on." Steve coaxed gently. The unconscious man slowly clawed his way to awareness. Two dazed eyes eventually fluttered open.

"Wha'?" Danny asked, wincing and trying to grab his head.

"Easy, Danny. You got hit pretty hard in the head. How do you feel?"

"Hit? Don' remember…"

"That's okay, Danno. How do you feel?"

"Head hurts. Dizzy." Steve frowned, then pulled out his phone…which had fallen out of his pocket. He checked Danny's pocket for his phone, but it was broken, probably from when he went down. Steve swore.

"Okay, partner. Looks like calling for help isn't really an option. I'm gonna get you to the car and we'll drive to the hospital, alright? Think you can manage that?"

Danny nodded, regretting the movement almost immediately as pain lanced through his skull and his vision tripled.

"Wha' 'bout him?" Danny slurred, pointing towards the man Steve had cuffed. _At least he can still recognize that he's a suspect_, Steve thought.

"I'll call for Duke to pick him up as soon as we get to the hospital. Come on, I'll help you up, then you just let me take the weight, okay?" They made their way awkwardly to the Camaro, which stood out absurdly in the dirty forest, and Steve gently deposited Danny in the passenger seat. As he climbed in behind the wheel, he heard Danny mutter something that sounded suspiciously like "Always gotta drive _my_ car". Steve smiled. Now _that_ sounded like Danny. Steve flipped on the siren and lights, then tore out of the clearing towards Honolulu. The miles flew by in a blur. Danny should have made some comment about Steve's driving and that he had a daughter by now, but he was eerily silent. Steve glanced over to see Danny's eyes closed and his head leaning against the window.

"Danno, you with me buddy?"

"Mmmmph…"

"Come on man, stay awake. We're almost there."

"'kay." Danny mumbled. A few minutes later, a particularly rough patch of gravel roused Danny. "Huh? St-steve? Where 'm I? Wha's 'appening?" Steve nearly crashed the car in surprise.

"It's okay Danny. You got hurt, but we're on our way to the hospital. Chin and I are gonna find the guy who did this to you, don't worry."

"'kay. What 'bout Kono? Can she help?" Danny asked. Steve's heart sped up.

"Danny, Kono's not here. You know that."

"I do? Where is she?" Steve felt himself apply a little more pressure to the gas pedal.

"She's in China. With Adam, remember?"

"N-no…why China?" Danny asked as the Camaro raced into the hospital parking lot. The more he tried to figure out why Kono was in China, the more agitated he seemed to get.

"Shh, it's okay Danny. We're here now. HEY! I NEED SOME HELP, NOW!" Steve yelled to the nurses. They rushed forward with gurney and a doctor in tow.

"What do we have?" the doctor asked as he examined his new patient.

"Detective Daniel Williams, 38, blunt force trauma to the back of the head. Extremely confused. Complaining of dizziness and pain. Having some issues with memory, too." Steve spouted off quickly on one breath. The doctor nodded.

"Okay, call radiology and let's prep him for x-rays and MRIs. I want to eliminate the possibility of a skull fracture or brain bleed before we continue." As they pushed the gurney through the hallways, a nurse held Steve back.

"I'm sorry, sir, but you'll have to go to the waiting room while we examine him."

"No, but that's my partner! He needs help-"

"And we will help him, but we can't have any unauthorized personnel back there. Your partner is in good hands, sir. Let us take it from here." And just like that, Steve was left alone as the mass of doctors and nurses around Danny moved as one away from him. He found the waiting room, filled out the necessary paperwork, and, after he called Duke, dialed Chin's number.

"_Hey, Steve. Did you and Danny find-"_ Chin began, but Steve cut him off.

"Danny's hurt. He took a pretty nasty blow to the head."

"_Where are you?"_

"HMC."

"_Alright, I'm on my way. What the hell happened?"_

"We tracked the cell signal to a tunnel system, but Danny couldn't go in."

"_Because of his claustrophobia, yeah._"

"Danny told you and not me?"

"_He didn't exactly tell me, it's just something I noticed. Anyway, what happened after that?"_

"I went in, but I ended up chasing our guy out. And right by the entrance of the tunnel, Danny's laying there. I don't know what happened exactly, but it looks like someone clubbed him over head with something. I lost my cell in the tunnels and Danny's broke when he fell, so I had to drive him here."

"_Jesus…how is he?"_

"The doctors are still with him, but he wasn't looking too good last time I saw him. He was really confused. Chin…he was asking where Kono was." Steve could hear Chin blow out a breath of tension.

"_That bad, huh? I'll be there in about five minutes, just hold on."_ After Chin arrived, Steve filled him in on everything that had happened in the forest.

"You know, that area is full of homeless addicts. Maybe one of them saw the badge and freaked." Chin speculated.

"Yeah, maybe." Steve said distractedly. To take their minds off of the situation, Chin told Steve about Catherine coming to him with the information on Sato's man in Hawaii. They spent the better part of two hours talking about possible ways to get Kono home and another in silence. When the doctor finally approached them, their nerves were frayed.

"Are you Commander McGarrett?" the doctor asked.

"Yeah, how did you know?"

"Detective Williams told me you'd be the guy who looked ready to start World War III and had an aneurysm face. He also said that you were a 'Neanderthal Animal' if I heard that right." Steve couldn't help laughing.

"He can't be too bad then if he's already talking like that."

"So that's normal for him?"

"Absolutely." Chin confirmed with a smile. The doctor laughed and offered his hand.

"I'm Kevin Hoshino, I've been treating Detective Williams since he came in." they all shook hands as Hoshino took a seat opposite them.

"So how is he, doc?" Steve asked, slightly less nervous than before.

"Basically, he got his eggs scrambled a bit, but he should be fine. Nasty concussion, but nothing he won't recover from. The confusion was short term and, though he's still unclear about the details, he's fully aware now." Steve let out a breath he hadn't even realized he had been holding. After he had explained everything, Hoshino took them to Danny's room. Danny lay sleeping on the bed. The lights were off. Only a small lamp in the corner provided nay illumination.

"Hey Steve." Danny mumbled tiredly.

"How did you know it was me? Your eyes are closed."

"Your footsteps are all stompy." Chin chuckled.

"Oh, Chin's here too. Party…" Steve smiled.

"How ya doin' partner? You look a lot better than before." Steve remarked, taking in the clean white bandage wound around Danny's head.

"Okay. Head hurts like a bitch, but s'not my first concussion."

"Yeah…" Steve said, remembering all of the head injuries Danny had suffered in the few years he'd known him. "We'll let you rest, Danno. Feel better, alright? I'll be by tomorrow to pick you up."

"Sounds good. Thanks babe."

**But wait, there's more! will be posted soon! I plan to finish this tonight! Beware the plot twists!**


	2. Chapter 2

**Ok, I lied. I said I was gonna get this done last night, but obviously I didn't. In my defense, Mitch said that it was required by law for me to see Forrest Gump, so I didn't want to break the law or anything.**

Two weeks passed without incident. Danny's concussion faded and he returned to work. They never were able to discover who had actually hit him, but they felt Chin's homeless addict theory was the most plausible. It wasn't until Steve and Danny were driving to a crime scene that Steve began to notice something was off.

"Steve, aren't you gonna get that?" Danny asked, irritated.

"Get what?" Steve replied, thoroughly confused.

"Your phone. It's been vibrating for the last ten miles." Steve glanced at Danny, his brow furrowed.

"My phone's not ringing, Danny. Neither is yours. You alright?"

"You sure? Huh. Must be all that coffee I had this morning. Grace decided to go shopping for me and she picked out some super caffeinated brand."

"Yeah, ok." Steve said, not quite believing it. The rest of the day he watched his partner closely, noticing small things that, cumulatively, were really starting to worry him. Danny had always been a bit of a hot head, but he seemed far quicker to anger no than ever before. Multiple times over the course of the day, he watched Danny complain about some nonexistent noise. And when he thought no one was looking, Steve could see him try to massage the pain in his head away. When this persisted into the next day, he brought his concerns to Chin. On the third day, Danny stopped showing up for work. The first time, Danny left Steve a short text saying he wasn't feeling well and would be staying home. The next day, there was nothing. Now on the verge of panic, Steve drove like a maniac to his friend's house. When he knocked on the door, there was no answer. Pulling out his key, Steve entered the house.

"Danny?" he called, hoping he would find him asleep instead of something worse. There was no answer. "You sleepin' man?" No answer. "I've tried calling you a million times. Did your phone die?" Steve tried one more time. When he received no response yet again, he began to pull his gun, but stopped when he heard labored breathing coming from the basement. He flew down the stairs and found himself face to face with the barrel of a gun. His eyes followed the arm holding the weapon back and he was shocked to see that it was Danny, his partner and brother for all intents and purposes, pointing the gun at his face.

"Danny," Steve said, slowly raising his hands in a non-threatening gesture. "what's goin' on? Come on, why don't you put the gun-"

"Shut up! Just shut up McGarrett!" Danny yelled, his gun arm dipping and shaking before centering once more on Steve's head. McGarrett? Since when had Danny called him that?

"Danny, I'm just here to help, okay?"

"How…how do I know you're not one of them?" Danny looked truly crazy at this point. Pale and shaky, twitching every once in a while. It hurt Steve to see his friend that way.

"Ok, how can I prove to you that I'm on your side?"

"On the day Grace and Rachel were carjacked, you told me I had something. What did you say I had?" It took Steve a moment to realize what Danny was asking, but as soon as he did he almost smiled.

"I said you had a tone. Danny, right now your tone is scaring the hell out of me and so is that gun." This seemed to calm Danny a bit, so Steve took a chance. Wrapping his hands around the gun, he gently took it from his friend's grasp and tucked it in his waistband. "Come on, Danno. Let's put this away, alright? Now can you tell me what's wrong?" To Steve it looked like Danny was having so sort of psychotic break.

"They're everywhere, Steve." Danny said, his voice a whisper as if afraid 'they' might hear him.

"Who are they, Danny?"

"I don't know! But they're in my head! But they can't find as easily down hear. Safe down here…" Danny muttered as he started to pace and wave his arms. It was then that Steve noticed the blood beneath Danny's fingernails and the angry scratch marks at the base of his head. Even as he watched, he saw Danny scratch at it roughly as if he were trying to dig something out.

"Danno, why don't we get you a hospital?"

"No! They can find me there!"

"Hey hey hey, I'll be there, okay? They won't find you, I promise. But the doctors might be able to figure out how they got in your head." Danny considered this for a moment.

"Okay…" he followed Steve timidly out of the basement. The moment they reached the top of the stairs, his hands flew to his ears and he bent nearly double.

"Danny? Danny, what's wrong?"

"I can hear them! God, it's so loud!" Steve felt close to panic as he tried to put together the pieces. Brain tumor? God, he hoped not. He practically had to carry Danny out to his truck. The entire ride to the ER, Danny spent holding his head. As soon as they arrived, the doctors and nurses for the second time in two weeks took him away and pushed Steve back to the waiting room. Once again, he filled out the paper work and once again, he called Chin.

"Steve!" Chin yelled, running into the waiting room. "What happened?"

"I don't know. I went over there, and he was hiding in the basement. And as soon as I got down the stairs, he pointed his gun at me. Chin, he sounded crazy. Actually insane. He was twitching and going on about these people who were everywhere. And I have no idea really what caused this."

"He'll be okay. I'm sure there's an explanation for this." Chin said, ever the voice of reason.

"I hope you're right."

**Shortish chapter, but there's more comin' so don't get your panties in a wad. Thanks for all the reviews! You guys are awesome!**


	3. Chapter 3

**Another chapter! Possibly the last one, I'm not sure. I sure hope you're enjoying my take on this! And I will finish my other stories once this is done, I promise!**

Two hours later, a young doctor came out and found them. Instead of the smile that Danny's last doctor had worn, her face was pinched with anger.

"Are you here for Detective Williams?" she asked. They nodded. "Dr. Lindsay Rothmeyer. I've been overseeing Mr. Williams' care."

"What's going on? Why was he acting that way?" Her eyes flashed in anger once more as she pulled a small plastic container out of her pocket.

"This is why." She said, allowing them to see the contents of the container. Inside was a small piece of what looked like plastic.

"Is…is that a computer chip?" Steve asked incredulously.

"Yes. We found that inserted just under the skin in Mr. William's head. We believe it was put in there when he was getting stitched up after his last head injury two weeks ago."

"His doctor…" Chin began.

"Yes, we think Dr. Hoshino was the one who planted it." Her disgust with her colleague was evident.

"What exactly would this do to him?" Steve asked.

"Preliminary tests show that when sent a signal, the chip emits sounds and electric pulses that only he Mr. Williams would have been able to hear and feel. The vibrations of these noises are enough to cause temporary insanity in anyone. We believe that this was all directed at the amygdala. It's the part of the brain that-"

"Deals with social skills and moral behavior." Steve finished, remembering the case they had been working when Danny had been injured. "But Ellery's dead. If this is his research, who's doing the experiments and why Danny?" he asked Chin.

"I don't know. Hoshino maybe. But I think I know why Danny was hiding in his basement. You said that the chip is only active when sent a signal?" Rothmeyer nodded. "Then the walls of the basement would have blocked out the signal, at least partially." Steve nodded, then turned to Rothmeyer.

"Do you know where Kevin Hoshino is?" she shook her head.

"No, the bastard stopped showing up for work a week ago." She said bitterly. "But we do have an address on file." she handed Steve a piece of paper with all of the hospital's information on Hoshino.

"Thank you. Really."

"Anything to get him off the streets. Doctors are supposed to be the ones we can trust and that son of a bitch is experimenting on his patients? Damn right I'll help in any way I can." Steve smiled at her.

"So how is Danny?"

"Exhausted, dehydrated, but there should be no long term effects. We did have to sedate him in order to remove the chip, but we got it out with no problems. He's resting in a private room right now. We have him on a few IVs, but they'll come off soon enough." She gave them the room number, then left to attend to her other patients. Knowing that Steve would call if anything changed, Chin took the chip and left for Charlie's lab. Steve continued on to Danny's room. He believed Rothmeyer, but he needed to see for himself that Danny was okay. He sat in the hard plastic chair and waited for his partner to open his eyes. After half an hour, Danny stirred.

"Mmmphh…Steve?" Steve's head shot up and he donned his trademark goofy smile.

"Hey Danno! How ya feelin'?

"Fine, I guess. You wanna explain why I'm back in the hospital Steven?"

"You don't remember?"

"No…what should I be remembering?"

"Depends. What's the last thing you did?"

"Uhhhhh…getting the oil changed on the Camaro."

"That was four days ago."

"I've been out for four days?"

"Not exactly. But you haven't really been yourself."

"What do you mean?"

"Well, you kinda went…crazy."

"So…where's the straight jacket and rubber room?" Danny joked halfheartedly. It was obvious that he was confused and a bit scared.

"It's not like that. It wasn't your fault. You can blame Dr. Hoshino for this." Steve spat out with venom in his words.

"Hoshino…you mean the doctor who stitched me up after I got conked over the head?"

"Yeah. He put this chip in under your skin before he closed up the wound. Looks like he was experimenting with continuing Ellery's work. The chip put out these noises and electric pulses that messed with your head."

"Bad enough to put me in the hospital?"

"Danny, you called me McGarrett, pointed your gun at me, and almost blew my head off." Danny stared at him.

"Jesus…sorry man." Steve chuckled.

"It's okay. Believe me, I could tell it wasn't really you doing that."

"Even so, what if I had shot you?"

"Hey, you didn't, okay? So let's not think about that."

"Yeah…so, you've got a plan to take Hoshino down, right?"

"Oh yeah we do, buddy. I've had Chin going over his life with a fine tooth comb and we found some interesting stuff. Like large purchases of medical equipment and part for chips just like the one that was in your head. Hoshino's also paid for a contractor to discreetly dig him a larger basement. Combine that with his other purchases, we think he's built himself a lab underneath his house. According to the staff here, he hasn't been to work all week. I've got HPD surrounding the place secretly right now. In about forty-five minutes, Chin and I are gonna see if the good doctor's home." Danny raised an eyebrow.

"That half assed piece of shit is your plan? Only you would consider that well thought out." Danny grumbled.

"Hey, if I remember correctly, my half assed 'McGarrett Plans' as you call them almost always work."

"Yes, but do you remember the times they failed? Because when they fail Steve, they tend to fail rather spectacularly and usually end with explosions and someone getting shot!" Danny practically yelled. Steve could see the concern behind the anger. He knew his partner felt guilty about not being able to have his team's back. That's what Danny was best at. He was the backup and, over the years, he had come to embrace that role. It was in his nature to be loyal and protective.

"We'll be careful, Danny. I promise."

"You better be." Danny said, a small smile showing Steve how much he needed them to be safe.

**One more chapter after this. It got a little longer than I thought it would, but if ya got something good, go with it!**


	4. Chapter 4

**Hello people of ! Mitch here! For those of you who don't know me, I'm HipsterMaybe's boyfriend. She wrote this chapter out in a notebook while in the car yesterday, so while she is sick with the flu, I've decided to update this for her. Please pardon any spelling and grammar mistakes. Honestly, the only reason I even passed high school English was because of her. Anyway, I'm sure she'd say something like "I really hope you enjoy this" and I think she'd really appreciate some reviews here. Thanks! ~Mitch**

Exactly one hour later, in the anally precise McGarrett manner, Steve marched up to the front door of Kevin Hoshino's impressive house. When he received no answer, he casually nodded to Chin, then shot the lock off the door. Ignoring the stares from the surrounding members of HPD, the two men entered the house. Ignoring the main floor, they immediately went for the hidden entrance to Hoshino's lab. The blueprints of the additions the private construction company who had done Hoshino's basement had been given to Five-0 without issue once Steve threatened them with aiding and abetting. Steve didn't even know if he could charge them, but Ridgecrest Specialty Construction didn't know that. Once Steve and Chin had found the door disguised as a bookshelf, they descended the stairs before them. The lab that greeted them was bathed in harsh fluorescent light. With feline stealth, they approached the man hunched over a computer with his back to them.

"Kevin Hoshino," Steve growled in a low menacing tone. "you're under arrest for the illegal conduction of experiments on unwilling participants. Put your hands behind your head and interlock your fingers. Do it now." Hoshino complied, then stood and turned to face them.

"You're making a mistake, Commander. I am not the bad guy here."

"Oh yeah?"

"On the contrary. _I_ am trying to fix the criminal mind. Rehabilitate it."

"Just like William Ellery?" Chin asked coldly. Hoshino snorted.

"Bill was a crock. He never would have been able to crack the science."

"There is no science to this. You almost killed someone." Anger flashed through Hoshino's eyes.

"Because you interrupted the experiment! If it had had time to run its course, even if it had failed, I would have learned and been able to perfect it. I had just been looking over the research and when Detective Williams came in, it was the perfect opportunity. Just because Ellery's method was flawed, doesn't mean his basic idea was! If the amygdala could be properly stimulated, it could be shaped and molded into a more stable person. I was going to figure this out!"

"No matter how many people died in the process?" Chin said, his anger matching Hoshino's.

"Yes." The doctor replied firmly. Steve felt his trigger finger twitch. _It would be that easy…_no. That wasn't him. He wasn't a cold blooded killer like Hoshino.

"You have the right to remain silent." Steve said quietly, beginning to cuff Hoshino. "Anything you say can and will be used against you in a court of law. You have the right to an attorney. If you cannot afford an attorney, one will be provided for you by the court. Do you understand these rights as I have read them to you?" Steve asked in a dutiful and lawful manner that Danny would be proud of.

"Just one question. How fast are your reflexes?" Hoshino smiled and with his one hand that was not yet cuffed, he grabbed a nearby by scalpel and plunged it into Steve's shoulder. Acting purely on instinct and adrenaline, Steve responded with a vicious uppercut to the solar plexus and a blow to the head with the butt of his gun that rendered Hoshino unconscious.

"That's for Danny, you son of a bitch." Steve spat out, then winced as the pain let itself be known. Breathing through the pain, he still managed to give commands. "Agh! Chin…get HPD down here to arrest him and…go through the lab…have them see if anyone else…has a chip in their head. And then…if you have time…I'd really like a ride to the hospital."

H

5

0

Danny raised an eyebrow as Steve walked into his room, arm in a sling.

"What did I say about being careful, Steven?"

"Oh, come on. I was careful!" Steve defended.

"Mmmmhhhmmm…Chin?" Danny asked, nodding his head towards Steve.

"He actually followed protocol. Read him his rights and everything." Chin said with a disbelieving shake of his head. Danny smiled.

"Looks like I finally managed to teach you something. You okay, babe?" Danny asked as Steve rubbed his shoulder.

"Yeah, I'm good. Docs said it should heal up just fine. How's the head?"

"Better now that I don't feel like I'm going insane."

"Well that's good, 'case I have had just about enough of you scaring the hell out of me. First the concussion and then with the almost shooting me."

"I'm with you there." Chin said.

"I'm glad you guys are okay." Danny said seriously.

"Right back at ya, brah."

**The End! Well, I personally liked the ending, but maybe I'm biased. She said she thought it was terrible, but she's always so hard on herself. Hipster also asked me to put in here that she will finish Cat and Mouse very soon and that she will most definitely continue Nalowale Kane!**


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